Port 827 sits in the well-known port range (0-1023) but has no official service assigned by IANA.1 It exists in a peculiar state: reserved by position, but unclaimed by protocol.
The Well-Known Range
Ports 0-1023 are called "well-known ports" and are typically reserved for system services and widely-used protocols. Assignment requires IANA approval. Port 827 falls within a block (811-827) that remains unassigned in the official registry.2
Being in this range means that on Unix-like systems, only privileged processes (running as root) can bind to port 827. This restriction exists even though no official service claims it.
The Unofficial Story: NetInfo's Legacy
While IANA lists port 827 as unassigned, it has historical significance in the Apple ecosystem. Port 827 was used by Mac OS X for RPC-based services, particularly NetInfo—a hierarchical distributed database inherited from NeXTSTEP.3
NetInfo managed administrative data: user accounts, groups, email configurations, network filesystems, printers, and other system resources. It was the backbone of system configuration on early Mac OS X versions.
But NetInfo is gone. Apple removed it entirely in Mac OS X 10.5 Leopard (2007), replacing it with Open Directory.4 Yet port 827 remains in the well-known range—a fossil from when Macs spoke a different administrative language.
Why Unassigned Ports Matter
Unassigned ports reveal something about how the Internet evolved. The well-known range was established when 1,024 ports seemed abundant. Some were claimed immediately (HTTP on 80, SSH on 22). Others, like 827, were reserved by position but never officially allocated.
These gaps serve a purpose:
- They provide space for future standardized services
- They're sometimes used informally by applications (as NetInfo did)
- They demonstrate that not every number in a namespace gets used
The existence of port 827 is a reminder that protocol design involves not just what gets assigned, but what gets left open.
Checking What's Listening
To see if anything is using port 827 on your system:
On Linux/Mac:
On Windows:
If you're running a modern Mac (post-2007), you almost certainly won't find anything. NetInfo is history. Port 827 is quiet.
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